The present invention relates to a medium transporting device which transports a medium and a recording apparatus provided with this medium transporting device.
Heretofore, for example, in an ink jet printer that is one of recording apparatuses, while paper that is one of recording media is being fed into a recording section by a paper transporting device, recording is performed and thereafter the paper is fed out to the outside. In such the ink jet printer, while the paper is fed in a state where it is held between a feed roller and its driven roller, recording is performed in a recording head, and thereafter the paper is fed out in a state where it is held by a discharge roller and a spur roller functioning as its driver roller, and discharged.
In the ink jet printer including such the paper transporting device, in case that an image composed of ejected many ink droplets, for example, a solid image is recorded on the paper, the paper absorbs a large amount of ink, so that it bulges toward the recording head in the wavy shape after recording, that is, cockling is produced. As this cockling develops, the distance between the paper and the recording head becomes more uneven, and unevenness is produced in ink splash distance, whereby unevenness is produced in recording, or the paper comes into contact with the recording head and stains. Therefore, recently, an ink jet printer has been proposed, in which plural openings are formed on a paper transporting surface in the paper transporting direction and in the direction perpendicular to the paper transporting direction at a regular pitch, that is, the plural openings are provided in the shape of a grid, and the paper is sucked through these opening by a suction pump thereby to suppress the above cockling (refer to JP-A-63-303781 and JP-A-3-270).
In the ink jet printers including the above conventional suction type paper transporting device, there is an ink jet printer having a dimple around each opening in order to heighten suction force determined by negative pressure×area. However, since the dimples are formed in the shape of a grid correspondingly to each opening, a partition wall exists between the dimples. Therefore, after a leading end of the paper a medium was pulled into the dimples once, it is curled up by the partition walls provided in the direction perpendicular to the paper transporting direction, so that there is fear that it comes into contact with the recording head and stains.
Further, in the ink jet printers including the above conventional suction type paper transporting device, through-holes are only opened on the paper transporting surface to suck the paper. Therefore, it is difficult to suppress cockling throughout the entire surface in the recording section by a proper amount of suction force. On the contrary, in case that the suction force is too strong, though cockling can be suppressed throughout the entire surface, decrease of feeding accuracy can be caused.